1. Field of the Invention
This invention relates to an apparatus for winding webs on core tubes, which apparatus comprises mutually opposite trunnions, which are aligned with each other and rotatably mounted in a machine frame and at their confronting ends are provided with mandrels, which are adapted to be inserted into the core tubes and to be forced against said core tubes, wherein each of said trunnions is mounted in an axially displaceable bearing sleeve and the apparatus also comprises drive means for axially reciprocating at least one of the mutually opposite trunnions.
2. Description of the Prior Art
U.S. Pat. No. 32,79,716 discloses a so-called reversing winder, which is provided with a peripheral drive and in which a shaft that is rotatably mounted in the machine frame is provided with mutually opposite carrying arms, which are 180 degrees and are provided each at their free ends with aligned trunnions, which are provided at their inner ends with fixed mandrels, between which the core tubes are held. To permit the core tubes to be fitted on the mandrels of rotatably mounted trunnions and to permit the wound complete coils to be removed, the trunnions must be axially slidably mounted so that they can be moved apart to such an extent that the tubes with the coils are released by the mandrels.
Swiss Patent Specification No. 464,965 discloses an apparatus which is of the kind described first hereinbefore and in which the trunnion which carries the mandrel is rotatably mounted in a bearing sleeve, which is axially slidably mounted in a bore of a carrying arm axially slidably mounted in a bore of a carrying arm of a coil changer. Owing to that arrangement the trunnion can be extended and can be retracted to such an extent that the mandrel is almost entirely received by the bore of the trunnion. That known apparatus may operate satisfactorily if the length of each core tube and of each coil is approximately as large as the distance between the trunnions so that the core tubes can be mounted and the coils can be removed when the trunnions have axially been displaced by a length which equals the length or twice the length of the mandrels. Owing to said small displacements the trunnions can be rotatably mounted closely behind the mandrels so that the trunnions have only short lever arms and will oppose a deflection of the trunnions under the weight of the coils and under the additional pressure forces exerted by possibly provided pressure-applying rollers or pressure-applying belts.
But if an apparatus of the kind known from Swiss Patent Specification No. 464,965 is required to produce a coil which has a small length and is large in diameter, it will be necessary for the bearing sleeve and the bore in the trunnion to have such a large length that the core tube can be sufficiently extended. But a bearing sleeve which has been extended to a large extent from the bore of the carrying arm will be subjected to strong bending forces so that the bearing sleeve must be sufficiently large in diameter for taking up such forces. As a result, the bearing sleeve may be larger in diameter than the mandrel and the pressure-applying rollers or pressure-applying belts must not be wider than the web which is to be wound up because otherwise the pressure-applying rollers or pressure-applying belts would bear on the bearing sleeves rather than on the core tubes which have been fitted on the mandrels. Another requirement to be met by a winder at the beginning of the winding operation resides in that the mandrels connected to the trunnions can be replaced by adapters which differ in diameter so that core tubes which are relatively large in diameter can also be used. In the apparatus disclosed in Swiss Patent Specification No. 464,965 the diameter of the mandrel or adapter must not exceed the diameter of the bearing sleeve so that the mandrel can be received by the bores of the carrying arms as the trunnions are moved apart. If larger mandrels or adapters were used, it would not be possible to wind coils which are so long that they occupy the entire space between the carrying arms because the usable space would then be reduced by the length of the mandrels.